1. Field of the Invention
The invention relates to an electrical plug connection, particularly for motor vehicle applications, comprising a plug housing, a contact housing complementary to the plug housing and a bayonet ring for locking the plug housing in the contact housing.
2. Description of the Prior Art
Plug connections of this kind are mounted mainly in a corresponding wall of a housing, so that the electrical connections of the device in the housing are led out. For example, plug connections of this kind are used as pre-cabling for motor vehicle transmissions. It is particularly in the area of motor vehicle transmissions that very intensive vibrations occur so that care must be taken to ensure that the plug connection cannot automatically work loose.
Known plug connections have locking devices for securing the plug housing in the contact housing. During assembly care must be taken to ensure that the locking device fully engages. It may happen in practice that the locking device is brought only into an intermediate position, in which although the plug housing has been inserted in the contact housing the locking device is not in the closed position so that the plug connection can automatically work loose, for example due to the high vibrations.
The object of the invention is to provide an electrical plug connection wherein incomplete locking of the plug parts due to assembly errors, with the consequent release effects, are reliably avoided.
This problem is solved by the features the present invention.
The electrical plug connection according to the invention comprises a plug housing, a contact housing complementary to the plug housing and a bayonet ring for locking the plug housing in the contact housing. At least one spring element acts on at least one movable rotary slide and, when the bayonet ring is turned so as to close it, exerts an increasing stress on said bayonet ring and, in the event of the bayonet ring being incompletely turned to close it, unturns the latter into its open position. The bayonet ring is locked in its closed position only when it is completely turned so as to close it.
The effect of the co-operation of the bayonet ring, spring element and rotary slide according to the invention has the effect that the electrical plug connection and its locking device (bayonet ring) are always in a defined state and this state is unmistakably indicated to the fitter. If the bayonet ring is incompletely turned to close it, the coupling of the rotary slide with the bayonet ring by way of the spring element causes the rotary slide to exert a force on the bayonet ring which after the manual rotary force has ceased automatically unturns the ring into its open position. The fitter is thus shown that the bayonet ring has not been engaged and hence cannot fulfill its securing function.
Another special feature of the invention is that when the bayonet ring is turned to close it, the two housings (plug housing and contact housing) of the plug connection are brought together, this being achieved by the configuration of guide grooves on the plug housing to receive studs on the bayonet ring.
This leads to the advantageous possibility of making the connection between the electrical contacts of the plug housing and the electrical contacts of the contact housing only when the bayonet ring has been turned so as to close it. If the housings are just plugged together with the bayonet ring in the open position, there is no electrical connection between the contacts. The bayonet ring occupies two defined positions, i.e. the open position and the closed position, because of the restoring force of the spring element. The configuration of the guide groove has the effect that the two housings are brought together when the bayonet ring is turned to close it, or are moved apart when the bayonet ring is turned to open it. Similarly the electrical contacts of the two housings are brought into electrical connection during the turning in the closing direction and separated on turning in the opening direction. There is accordingly a direct relationship between the position of the bayonet ring and the electrical connection of the corresponding electrical contacts of the two housings. Thus in the closed position the contacts are interconnected while in the open position they are not. If current now flows through the plug connection, it is simultaneously confirmation of the bayonet ring having been turned so as to completely close it.
The retaining elements can be so designed as to withstand the force of the stressed spring. The bayonet ring remains in the closed position, although with the disadvantage that the spring is constantly stressed. This unwanted effect can be avoided by unstressing the spring element just before the bayonet ring engages the plug housing, and this can be achieved by a projection to lift a hook of the spring tongue.